How we calculate your targets
Last Updated: September 25, 2026
Your calorie and macro targets are not guesses and not a template. They come from the same methods a dietitian uses, adjusted to you, with safety limits the app will not cross. Here is how, in plain language, with the sources at the end.
These targets are a starting point for general wellness, not medical advice. You can change any of them in the app, and if you have a medical condition, are pregnant or nursing, or have a history of disordered eating, please work with a doctor or registered dietitian.
1. Your calorie target
What your body burns at rest. We start with the Mifflin-St Jeor equation, the resting-energy formula most dietitians use and the one a major review found most accurate for adults. It uses your age, height, weight, and sex. If you choose not to specify male or female, we use the midpoint of the two, and you can fine-tune the result yourself.
How active you are. That resting number is scaled by one of four standard activity levels, from mostly sitting to physical work all day, to estimate what you burn on a typical day.
Your goal and pace.
- Maintaining: your target is what you burn.
- Losing: you pick one of four paces. The fastest is capped at a deficit of about 1 kg (2.2 lb) a week, and every pace is scaled to the room you actually have above the safety minimum below, so each option stays safe and different from the others.
- Gaining: a modest surplus of 150 to 550 calories a day, the range where extra food mostly builds muscle rather than fat.
The floor. Your target never goes below 1,200 calories a day for women or 1,500 for men (1,500 if unspecified), the NIH minimums below which weight loss needs medical supervision. If your pace would take you under that, the app raises the target and tells you.
Weight loss is for adults. moonbelt is for people 18 and over, and it never sets a weight loss target for anyone younger.
2. Protein
Protein is set per kilogram of body weight, from 1.6 to 2.0 g/kg depending on your pace, the range sports nutrition research supports for keeping muscle while you lose fat or building it while you gain.
- Adjusted for body size. At a BMI of 30 or more, we use an adjusted body weight instead of your total weight, as clinical dietitians do, because muscle does not grow in step with body fat. Without this, targets for larger bodies come out unrealistically high.
- Never more than 35% of your calories. That is the top of the range the National Academies consider healthy.
- Never squeezed too low. On a tight calorie budget, protein keeps at least 1.2 g/kg before anything else gives.
- High protein style tops out at 2.0 g/kg, the upper end of what the International Society of Sports Nutrition describes as safe for healthy, active people. We do not go higher, because we do not screen for kidney disease.
3. Carbs, fat, and diet styles
Diet style changes the food, not the calories. Large studies, including the DIETFITS trial, found that low-carb and low-fat diets lose the same weight when calories match, and the American Diabetes Association finds no single ideal split. So your calorie target stays the same whichever style you pick. Only where the calories come from changes.
- Balanced and high protein: about 25% of calories from fat (never below 20%), at least 130 g of carbs a day, the amount the National Academies set as the baseline for brain fuel, and the rest from carbs.
- Low carb: carbs held to 100 g a day or 26% of calories, whichever is lower, the standard clinical definition.
- Keto: 40 g of total carbs a day, within the usual 20 to 50 g range. Because fiber counts inside those carbs, the fiber goal is halved on keto so it can actually fit. The app shows who should check with a doctor first.
Your three macros always add back up to your calorie target, so hitting every macro ring never puts you over on calories.
4. Fiber and daily limits
- Fiber: 21 to 38 g a day depending on your age and sex, from the National Academies.
- Sodium: under 2,300 mg a day, the general limit in the Dietary Guidelines for Americans.
- Saturated fat: under 10% of your calories.
- Added sugar: under 25 g a day for women and 36 g for men, from the American Heart Association.
5. The week, not the day
Your daily targets stay the same from day to day, but one day tells you little. Once a week, your review reads the last seven days together: which weekday your protein tends to dip, which nutrients stayed low all week, what went well, and one thing to change next week. No day ever gets a pass or fail.
6. What these numbers are, and are not
Every equation here predicts an average person like you. Real bodies vary, often by 10% or more, and weight changes more slowly than a simple calories-per-kilogram estimate suggests. Treat your targets as a well-founded starting point, watch your weekly trend, and adjust. The app lets you edit any target directly.
Food values from photos, voice, and databases are estimates too. See our Terms of Service for the full disclaimer.
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990.
- Frankenfield D, et al. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association, 2005.
- National Heart, Lung, and Blood Institute (NIH). Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults.
- Institute of Medicine (National Academies). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. 2005.
- Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 2017.
- Evert AB, et al. Nutrition Therapy for Adults With Diabetes or Prediabetes: A Consensus Report. Diabetes Care (American Diabetes Association), 2019.
- Gardner CD, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss (DIETFITS). JAMA, 2018.
- U.S. Departments of Agriculture and Health and Human Services. Dietary Guidelines for Americans, 2020 to 2025.
- Johnson RK, et al. Dietary Sugars Intake and Cardiovascular Health. Circulation (American Heart Association), 2009.
Questions about how your numbers were set? Email support@moonbelt.ai.